ST_GeomFromWKB 接受公认二进制表示和 Spatial 参考系标识,并返回几何图形对象。
语法
db2gse.ST_GeomFromWKB(WKBGeometry Blob(1M), cr db2gse.coordref)
返回类型
db2gse.ST_Geometry
示例
以下 C 代码段包含 ODBC 函数,这些函数嵌有将数据插入 LOTS 表的 DB2 Spatial Extender SQL 函数。
已创建了 LOTS 表,该表具有两列:LOT_ID 列和 LOT 复合多边形列, 前者唯一标识每个地块;后者包含每个地块的几何图形。
CREATE TABLE LOTS ( lot_id integer, lot db2gse.ST_MultiPolygon);
ST_GeomFromWKB 函数将 WKB 表示转换为 DB2 Spatial Extender 几何图形。 整个 INSERT 语句被复制到 wkb_sql 字符串。该 INSERT 语句包含参数标记以动态接受 LOT_ID 数据和 LOT 数据。
/* Create the SQL insert statement to populate the lot id and the lot multipolygon. The question marks are parameter markers that indicate the lot_id and lot values that will be retrieved at runtime. */ strcpy (wkb_sql,"insert into LOTS (lot_id, lot) values (?, db2gse.ST_GeomFromWKB (cast(? as blob(1m)), db2gse.coordref()..srid(0)))"); /* Allocate memory for the SQL statement handle and associate the statement handle with the connection handle. */ rc = SQLAllocStmt (handle, &hstmt); /* Prepare the SQL statement for execution. */ rc = SQLPrepare (hstmt, (unsigned char *)wkb_sql, SQL_NTS); /* Bind the integer key value to the first parameter. */ pcbvalue1 = 0; rc = SQLBindParameter (hstmt, 1, SQL_PARAM_INPUT, SQL_C_SLONG, SQL_INTEGER, 0, 0, &lot_id, 0, &pcbvalue1); /* Bind the shape to the second parameter. */ pcbvalue2 = blob_len; rc = SQLBindParameter (hstmt, 2, SQL_PARAM_INPUT, SQL_C_BINARY, SQL_BLOB, blob_len, 0, shape_blob, blob_len, &pcbvalue2); /* Execute the insert statement. */ rc = SQLExecute (hstmt);